Shellfish feel the burn: damage linked to atmospheric CO2

The excess CO2 we're adding to the atmosphere is increasing the acidity of the …

Last week, the National Academies of Science released a report on research of what has been called "the other carbon problem"—ocean acidification. Excess carbon in the atmosphere has been lowering the ocean's pH (increasing its acidity), which has the potential to severely alter the ocean's chemistry. The NAS report says that we're way behind in studying this problem, which wasn't even fully recognized until recently. Just how far behind we are is made clear by a paper that will be released this week by PNAS, which reveals that two species of commercially harvested shellfish are likely to already be suffering increased mortality due to ocean acidification.

The basics of ocean acidification are fairly simple. Roughly a third of the CO2 emitted by human activity has ended up dissolved in the oceans; some fraction of that has combined with water to form H2CO3, a weak acid. These reactions take place quickly enough that a drop in pH has been apparent in some long-term monitoring stations. Overall, current estimates are that the pH of the oceans have dropped by 0.1 units (pH is a logarithmic scale) since the beginning of industrial carbon emissions.

This may sound minor, but as the NAS notes, it is expected to cause a "suite of changes in ocean chemistry." Chief among them is a change in the availability of carbonate ions, which corals and shellfish use to build reefs and shells, respectively. With reduced access to the raw material for their homes, it's possible that these animals, which provide ecosystem services and food to humans around the globe, might fall under increased stress, and be more prone to population crashes.

According to the new paper, however, those concerns are already past their sell-by date: significant shellfish species are already having problems with ocean acidification.

Most of the studies of acidification's impacts have been done in prospective studies, in which a population of animals are exposed to an environment that represents likely future atmospheric CO2 concentrations. For example, we're a bit above 390 parts-per-million CO2, so a study might set up an environment where the levels are 750ppm, which we could hit by the end of the century. These studies have generally found that shellfish don't do well in this environment, suffering from malformations, loss of shell material, and increased mortality.

The authors of the new paper saw these as well, since they tested two species, the quahog clam and bay scallop, in concentrations of 750 and 1500 ppm. At the 750ppm level, basic shell structures like the hinge were severely malformed, while the surface of the shell had holes that were apparent when it was examined via scanning electron microscopy. There was also a significant drop in the viability of the larvae, and those that did survive were developmentally delayed compared to those raised at today's concentrations. Matters got worse at the higher levels.

The interesting twist in the new work is that the authors also run the experiment under preindustrial CO2 levels of about 250ppm (actual levels were closer to 280ppm). For both species of shellfish, the mortality was much lower and development proceded more quickly. For the quahog, viability doubled (from 20 percent to 40 percent), while for the bay scallop, viability went from 43 percent to 74 percent. The animals made major developmental milestones more quickly—metamorphosis at day 14 occurred in half the animals at preindustrial CO2 levels, but that dropped to less than seven percent at modern levels.

The authors helpfully point out that they've eliminated predation in their lab conditions. If the animals were subject to being eaten, the weaker shells that form at higher CO2 levels would almost certainly increase the mortality.

Overall, they suggest that population crashes in bivalves have been ascribed to a number of stresses, like overfishing and pollution, but it's possible that ocean acidification has also been at work in these cases. Given that the Earth has experienced higher CO2 levels in the past, why are they being hit so hard now? According to the paper, it's actually been over 24 million years since levels are likely to have been this high, and many shellfish have diversified more recently than that; any changes in CO2 in the intervening time have also been far more gradual than the current pace.

The fact that we seemed to have completely missed existing problems arising from ocean acidification provides some perspective to last week's NAS report, which suggests that the federal government has "taken positive initial steps" by setting up a program to study ocean acidification, but needs to make up for decades of neglect. We've already got an infrastructure in place to track changes in the ocean, but it was set up before acidification was widely recognized, so the equipment wasn't designed to monitor it.

The report suggests a number of priorities when it comes to future research and monitoring—"commercially important mollusks" like the ones in the study receive mention. And it points out that international cooperation will be needed to put an effective monitoring system in place. Finally, it emphasizes the need for a set of data storage and sharing standards to ensure that any results are accessible to the wider research community.

Even though we may have missed some of the impacts of this change in ocean chemistry, further changes are likely to occur throughout this next century, and coming to grips with them as soon as possible may enable us to adapt to or mitigate the most severe problems.

63 Reader Comments

I have to say, that shellfish pictures reminds me of a Dionaea muscipula (Venus Fly Trap) which in turn is a scary psychological reminder of a vagina dentata. But yes, the sea is going to get messed up with global warming, yet still people don't care.

this study really tells us little about what will happen...it just shows if you throw some animals in an environment that is more hostile then the one they have evolved in...more die...its not anything new...if i plant an orchid in a base soil...yeah its gonna hurt its chances of surviving and if it does survive i would not expect it to grow as big, strong and fast as one grown under optimal conditions...

i am not doubting the fact that acidification is happening in the oceans...nor that we should be studying it...but outside of gradually increasing the acidity of the water over generations of survivors makes this study hard to take seriously...i mean what else did the authors of this study expect?

You can "launch a solar shade" in the PC game Alpha Centauri, and that will make the ocean level fall. That is, it's a cure for global warming. Can anything be done from a climate engineering standpoint regarding this problem?

this study really tells us little about what will happen...it just shows if you throw some animals in an environment that is more hostile then the one they have evolved in...more die...its not anything new...if i plant an orchid in a base soil...yeah its gonna hurt its chances of surviving and if it does survive i would not expect it to grow as big, strong and fast as one grown under optimal conditions...

That's the difference between applied and pure science?

Regardless of how valuable you think the knowledge is, the climate is changing, the ocean's are changing, and someone needs to document how biomes are changing

jdietz wrote:

You can "launch a solar shade" in the PC game Alpha Centauri, and that will make the ocean level fall. That is, it's a cure for global warming. Can anything be done from a climate engineering standpoint regarding this problem?

Maybe we could just detonate an active caldera every ten years, and trigger temporary volcanic climate cooling?

You can "launch a solar shade" in the PC game Alpha Centauri, and that will make the ocean level fall. That is, it's a cure for global warming. Can anything be done from a climate engineering standpoint regarding this problem?

If you were to build a bunch of massive power plants (probably nuclear), you could use them to electrolyze water. Then you could take the hydrogen you got, and use even more power to heat incoming air to 650 C, combine with the hydrogen (in the presence of iron), and you'd end up with solid carbon and water. Of course, you have to worry about all the other reactions that would go on in the air as you heated it up (like the O2 reacting with the H2 you introduced, so make sure you've got enough H2 to use up all the oxygen), and it's sort of a massive energy investment. Even more so assuming that you want to replace the O2 you just used up (more electrolysis!), so you don't deplete the atmosphere of oxygen...

Humans = nature. Therefore whether climate change be us or not, its all nature. So nature is just performing harsh selection of the fittest... While it would be best if not everything simply died off, I'm more concerned with humans figuring out their own survival (including the survival of things we are sustained on). While the circle of life is good and all, there's no reason it has to be the "only" possible circle of life. Perhaps we are shrinking, or merely, changing the circle...Life is transitory by definition.

As the oceans are not acidic, I don't know how their acidity is increasing. Perhaps you mean their pH is increasing, or more technically their basicity is decreasing? Or perhaps more layman friendly but still accurate, the ocean pH is trending towards neutrality.

Humans = nature. Therefore whether climate change be us or not, its all nature. So nature is just performing harsh selection of the fittest... While it would be best if not everything simply died off, I'm more concerned with humans figuring out their own survival (including the survival of things we are sustained on). While the circle of life is good and all, there's no reason it has to be the "only" possible circle of life. Perhaps we are shrinking, or merely, changing the circle...Life is transitory by definition.

That... is a strange semantic argument.

Logically it would entail the revision of all murder statutes, since any human killing another would (by this definition) be a "natural" death.

As the oceans are not acidic, I don't know how their acidity is increasing. Perhaps you mean their pH is increasing, or more technically their basicity is decreasing? Or perhaps more layman friendly but still accurate, the ocean pH is trending towards neutrality.

Yes, there is an abuse of terminology here -- decrease in pH is not the same as decrease in alkalinity AT. (Note that acidity does have a formal definition as the negative of alkalinity).

The effect of decreasing pH on carbonate chemistry is real and as-described, however.

Humans = nature. Therefore whether climate change be us or not, its all nature. So nature is just performing harsh selection of the fittest... While it would be best if not everything simply died off, I'm more concerned with humans figuring out their own survival (including the survival of things we are sustained on). While the circle of life is good and all, there's no reason it has to be the "only" possible circle of life. Perhaps we are shrinking, or merely, changing the circle...Life is transitory by definition.

That... is a strange semantic argument.

Logically it would entail the revision of all murder statutes, since any human killing another would (by this definition) be a "natural" death.

"Your Honor, I would like to just like to state that the bullet did not kill the victim... The trauma did."

If you throw shell fish in pure nitric acid they die to. What is with the endless stream of scaremongering stories? In what sci-fi novel did they get the idea that CO2 levels would hit 1500 ppm when they say the current level is 390? Oh let me guess they have a computer model that predicts that. Only they don't have the data any more, wouldn't release it if they did and can't reproduce it.

I'm more curious about the tons of other crap we dump into our oceans. A couple million gallons of crude might make a tiny change. As might the garbage barges, or the many other toxic sludges we pump into our waterways. But hey, CO2 and climate change are all the rage, so why worry about the other things.

The Creation is so vast and intricate, only fools would think we will ever get it all figured out. But that doesn't stop us from f-ing around with it and monitoring the mess. Gene manips, antibiotics and hormone abuse, pesticide and dispersants by millions of tons, country-size plastic garbage patches in the ocean.

Add a little religion, overpopulation and economic system dogma and shake a little. Let's see what comes out of it.

I'm more curious about the tons of other crap we dump into our oceans. A couple million gallons of crude might make a tiny change. As might the garbage barges, or the many other toxic sludges we pump into our waterways. But hey, CO2 and climate change are all the rage, so why worry about the other things.

Right. Because studying and being aware of one problem automatically means that the other problems don't matter.

All of these things are happening at once. Dealing with any of them is good. Take your pick.

Quote:

While the circle of life is good and all, there's no reason it has to be the "only" possible circle of life. Perhaps we are shrinking, or merely, changing the circle...Life is transitory by definition.

Human beings are not sufficiently intelligent enough to conjure up a self-sustaining interdependent system like a planet-scale biosphere.

As the oceans are not acidic, I don't know how their acidity is increasing. Perhaps you mean their pH is increasing, or more technically their basicity is decreasing? Or perhaps more layman friendly but still accurate, the ocean pH is trending towards neutrality.

No matter where you are in the pH scale, lowering the pH makes a solution more acidic, in the same way that raising it makes it more basic. Hence, the formal name for the process, as adopted by the NAS: ocean acidification.

I try to be very careful to use it correctly, and not to imply that the oceans are becoming acidic, which is (as you note) a different thing.

If you throw shell fish in pure nitric acid they die to. What is with the endless stream of scaremongering stories? In what sci-fi novel did they get the idea that CO2 levels would hit 1500 ppm when they say the current level is 390? Oh let me guess they have a computer model that predicts that. Only they don't have the data any more, wouldn't release it if they did and can't reproduce it.

I hate to say this but this seems like classic misinformed skepticism.

Let me see if I can reduce your comment to the key facts:

jvillain: "Climate Change = scaremongering" article: "Here is some evidence due to the acidification of the ocean, its impacting sea life!"jvillian: Well duh, but that still doesn't prove anythingjvillian: "Let me present a straw man argument based on a non existent computer simulation–there is no way the scenario would ever happen!"jvillian: Climate Change not happening: QED

(jvillian: of course the scientist would just fudge the data or lose it when asked for it.... cause you know how dishonest and clumsy those climate scientist are)

How did those things fare when atmospheric CO2 levels were in the 1000's of ppm millions of years ago?

If you'd read the article more carefully, you'd see that "these things", as in the current species, probably didn't exist when CO2 levels were in >1000 ppm. The species probably never experienced CO2 levels like the present, according to the paper's authors.

Out in the middle of the oceans (unlikely, as they are linking it to shellfish), or in coastal regions, near habital areas where other factors (effluent, fertilisers, other man-made products) would be the major influence on the coastal waters - including acidity.

Or is it known that all the stuff we dump into our oceans (deliberately or through run-off) are pH neutral, or the same pH as the ocean?

Can anything be done from a climate engineering standpoint regarding this problem?

If you were to build a bunch of massive power plants (probably nuclear), you could use them to electrolyze water.... it's sort of a massive energy investment. Even more so assuming that you want to replace the O2 you just used up (more electrolysis!), so you don't deplete the atmosphere of oxygen...

But hey, that wouldn't hamstring human civilization and transfer wealth from the developed nations to the underdeveloped ones so we can all be poor together, so let's tax and trade carbon and socially engineer people to live more like third-world barrio dwellers instead.

As the oceans are not acidic, I don't know how their acidity is increasing. Perhaps you mean their pH is increasing, or more technically their basicity is decreasing? Or perhaps more layman friendly but still accurate, the ocean pH is trending towards neutrality.

No matter where you are in the pH scale, lowering the pH makes a solution more acidic, in the same way that raising it makes it more basic. Hence, the formal name for the process, as adopted by the NAS: ocean acidification.

I try to be very careful to use it correctly, and not to imply that the oceans are becoming acidic, which is (as you note) a different thing.

Dr. Jay, as I mentioned earlier, seawater alkalinity (and therefore acidity) has a well-defined usage and it is a slightly separate issue from pH lowering due to CO2 invasion.

Humans = nature. Therefore whether climate change be us or not, its all nature. So nature is just performing harsh selection of the fittest... While it would be best if not everything simply died off, I'm more concerned with humans figuring out their own survival (including the survival of things we are sustained on). While the circle of life is good and all, there's no reason it has to be the "only" possible circle of life. Perhaps we are shrinking, or merely, changing the circle...Life is transitory by definition.

Out of curiosity, are there any species that would do better (long term, and not as beneficiaries of a screwed up ecosystem) in a more acidic ocean?

I can think of an extreme example: The Shortfin MollyIt lives in essentially sulfuric acid. I found a nice article online that describes them but they are pretty rare.

For the vast majority of fish, most can only tolerate a certain ph drop before they die. That amount depends of course on the fish, but as evidence in the article(and plenty of others, just google it) this amount doesn't have to be much.

Dr. Jay, as I mentioned earlier, seawater alkalinity (and therefore acidity) has a well-defined usage and it is a slightly separate issue from pH lowering due to CO2 invasion.

You did mention that; unfortunately, the NAS, along with (as far as i can tell) most of the oceanographic community disagrees with you, and considers "acidification" the appropriate term. Sorry, but i kind of have to go with them.

I chose not to cover the NAS report last week - were you complaining then? I only rolled it into this report because it was relevant to the current paper. As for this paper vs. the one you're interested in, this paper was:a) more interesting.b) made available by the journal.

They will need to evolve and adapt. There is no difference between earthly changes where animals have to adapt and human intervention. It may take thousands of years before they can evolve to withstand new acidity levels but hey, it's a process.

Edit: Before anyone starts to argue against this, I realized that my joke may not have been obvious. So for those who are impaired, I have added this little tid-bit.

Dr. Jay, as I mentioned earlier, seawater alkalinity (and therefore acidity) has a well-defined usage and it is a slightly separate issue from pH lowering due to CO2 invasion.

You did mention that; unfortunately, the NAS, along with (as far as i can tell) most of the oceanographic community disagrees with you, and considers "acidification" the appropriate term. Sorry, but i kind of have to go with them.

There's a reason why I said the terminology was a problem. The Wikipedia intro on Alkalinity has a good summary of the problem:

Wikipedia wrote:

Alkalinity is sometimes incorrectly used interchangeably with basicity. For example, the pH of a solution can be lowered by the addition of CO2. This will reduce the basicity; however, the alkalinity will remain unchanged (see example below).

To read more about seawater alkalinity, I recommend the classic Dickson (1981).

In 2009, the combined U.S. production of corn, wheat and soybeans was 487 million metric tons. That production measures the usable part of the plants. It is reasonable to believe that there is at least as much material in unused stalks and leaves. If just this material were stored rather than burned or plowed under, it could compensate for almost a quarter of the U.S. carbon footprint.

But the numbers are only the case if your 487 million metric tonnes of non-usable parts of the plants are pure carbon. Ballpark figure for trees I know is that it's half water, and half of what's left (by weight) is carbon, so if that's anything like accurate (and the article's estimate of 50/50 usable/non-usable is appropriate) then this might be able to offset about 6-8% of US CO2 emissions. So while it might conceivably be part of a solution it could in no way pretend to be the only one.

The problem is soil nutrients. If you chuck the last generation of plant parts in a pile somewhere, you have to fertilize the soil for next year's crop that much more. At least as things stand, that means more mining, more transportation & processing, and fossil fuels used.

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But hey, that wouldn't hamstring human civilization and transfer wealth from the developed nations to the underdeveloped ones so we can all be poor together, so let's tax and trade carbon and socially engineer people to live more like third-world barrio dwellers instead.

The figures I've read both for damages and for that estimated to be sufficient to reduce demand to non-catastrophic levels are coincidentally quite similar, of the order of $30/MtCO2. Using 2007 figures, the US emits 5.8GtCO2/yr, so that'd be $174B/yr in taxes redistributed in your paranoid dream. US emissions are ~20% of the world total, and I recall estimates that the US would suffer about 2% of the world's damages due to climate change, so we can reduce the amount of money exported in your paranoid dream to about $160B/yr.

For a bit of context this is 1.1% of 2009 GDP, 42% of the 2009 trade deficit, or 74% of what was exported via the crude oil trade imbalance in 2009.

I'm not saying that $160B/yr is chump change, but I am saying that your idea of the reduction of the United States to the poorhouse via these means is a paranoid fantasy even within your wildest world-government-carbon-tax-international-redistribution paranoid fantasies.

"some fraction of that has combined with water to form H2CO3, a weak acid"

The actual reaction is CO2 + H2O -> HCO3- + H+. Carbon dioxide reacts with ocean water to form the carbonic acid anion, not the full dihydrogen carbonate, which won't form at that pH (~8.2). It's the addition of the proton here that causes the acidifiction.

Also - the point here about "it's not acidification because it's already basic" is stupid. It's like saying object is at ten kelvin and you heat it up, but that's not heating it's "experiencing less cold". Sorry guys.... addition of protons is acidification...

Interesting article. Now all we need are Wall-E's to cube the agricultural waste and stack it in huge towers.

Or, since the idea is to bury it thickly enough to prevent most decomposition at the bottom layers, perhaps we could just pick quarries and valleys and start trucking it in and packing it down much as we do with landfill garbage; except, as predominantly plant matter we wouldn't have to take environmental precautions like isolating it from the water table. We could ameliorate up to 1/3 of U.S. carbon emissions at a small fraction of the cost of CCS, much less economy-killing taxes or exporting our wealth to the ungrateful third world with carbon offsets.

this study really tells us little about what will happen...it just shows if you throw some animals in an environment that is more hostile then the one they have evolved in...more die...its not anything new...if i plant an orchid in a base soil...yeah its gonna hurt its chances of surviving and if it does survive i would not expect it to grow as big, strong and fast as one grown under optimal conditions...

i am not doubting the fact that acidification is happening in the oceans...nor that we should be studying it...but outside of gradually increasing the acidity of the water over generations of survivors makes this study hard to take seriously...i mean what else did the authors of this study expect?

Maybe you missed this whole paragraph, so I'll go ahead and quote it for you:

article wrote:

The interesting twist in the new work is that the authors also run the experiment under preindustrial CO2 levels of about 250ppm (actual levels were closer to 280ppm). For both species of shellfish, the mortality was much lower and development proceded more quickly. For the quahog, viability doubled (from 20 percent to 40 percent), while for the bay scallop, viability went from 43 percent to 74 percent. The animals made major developmental milestones more quickly—metamorphosis at day 14 occurred in half the animals at preindustrial CO2 levels, but that dropped to less than seven percent at modern levels.

If your argument were true, you'd expect mortality rates to go up under anything but present conditions, but they don't; going back to CO2 levels from only 200 years ago nearly halves their mortality. Therefore, the conclusion that dissolved CO2 levels correlate directly with increased mortality is totally valid.

You underestimate humanity's ability to make rapid and substantial changes to this planet's ecosystem, and you overestimate the ability of the ecosystem to adapt to these rapid changes. An almost doubling of dissolved CO2 levels in the last 200 years is a huge change; from an evolutionary standpoint, that timescale is a drop in the bucket.

Unfortunately, people are too ignorant to understand science and don't live long enough to really appreciate these changes themselves, so we're all totally screwed.